[M-IS17] Ocean Plastics, an earth science perspective

[MIS17-P13] Microplastic risk assessment based on polymer type in the coastal and open ocean areas around Japan

*Haruka NAKANO¹, María Belén ALFONSO¹, Suppakan JANDANG¹, Keiri IMAI³, Hisayuki ARAKAWA² (1.Research Institute for Applied Mechanics, Kyushu University, 2.Tokyo Univerisity of Marine Science and Technology, 3.Hokkaido University)

Keywords:Microplastic, FTIR

In order to understand the risk that MPs contamination to the marine environment, the Pollution Load Index (PLI), the Polymer Risk Index (H) and the Pollution Risk Index (PRI) were estimated. The risk assessment for five areas around Japan's coastal and offshore marine waters was based on the MPs abundance and polymer-type information recorded in situ. The abundance of MPs measured at each site ranged from 0.02 particles m-3 to 16.44 particles m-3, with higher values recorded near Tokyo's coastal area. Among the registered polymer types, polypropylene and polyethylene were dominant at almost all stations. According to H values (based on polymer type), the contamination due to MPs presented low to moderate risk in each area. Whereas the PRI (based on abundance and polymer type) classified the risk from low to very high, increasing from offshore to coastal areas where polymers with a higher risk exist and are more abundant. Furthermore, based on MPs' predicted concentrations for 2030 and 2060, the PRI risk due to MPs is expected to increase, reaching very high-risk values even for offshore areas. Based on these results, a precautionary approach should be considered to avoid potential impact on marine organisms. The results of this study emphasize the importance of action to prevent additional plastic pollution and the importance of continued monitoring of the MPs in the environment.